I know this thread is a bit old but was searching for some information and saw this and think I can comment on my recent experience.
I recently got the Flat Back Rib Half-Zip Pullover Vest in Black and Navy. I got the FJ logo on the collar. On the Black one the back of the FJ logo is white and blends in nicely with the inside of the collar which is white. On the Navy one the FJ logo is dark and is visible on the inside of the collar which is white. Both FJ logos are white on the outside of the collar and look great. I am not sure why they are different on the back given they are both white on the front.
I like these so much that I ordered more of each and will try to remember to post how those look and whether there is a reason my first two were different.
Hopefully after that I can help a bit more.